Drive belt for vintage lathe

[olderdan]

HI Philip, round bed Drummond's do not have half nuts as the lead screw is permanently engaged with the saddle, feed is done with the hand wheel at tail stock end. There is a simple dog clutch to engage the gear train if fitted just under the headstock pulley.
If this is stuck it may be rust or just gummed up, It is worth stripping and cleaning any old machine before use.
Lathes & co have a lot of info on it just search round bed drummond and it will come up.